Compressors are used to increase the pressure of a wide variety of gases and vapors for a multitude of purposes. A common application is the air compressor used to supply high-pressure air for conveying, paint spraying, tire inflating, cleaning, pneumatic tools, and rock drills. The refrigeration compressor is used to compress the gas formed in the evaporator. Other applications of compressors include chemical processing, gas transmission, gas turbines and construction.
Compressors can be classified as reciprocating, rotary, jet, centrifugal, or axial-flow, depending on the mechanical means used to produce compression of the fluid, or as positive-displacement or dynamic-type, depending on how the mechanical elements act on the fluid to be compressed. Positive displacement compressors confine successive volumes of fluid within a closed space in which the pressure of the fluid is increased as the volume of the closed space is decreased. Dynamic-type compressors use rotating vanes or impellers to impart velocity and pressure to the fluid.
New compressors under development include an oilless compressor for Joule-Thompson cryocoolers. Existing high-pressure compressors use oil as a lubricant and to remove heat, but the result is a waste-effluent problem and possible contamination that could clog the Joule-Thompson restrictor. Also under development is a magneto hydrodynamic compressor. The gas is compressed by a liquid gallium slug reciprocating in a narrow gap between the poles of a permanent magnet. An alternating current is fed through the gallium slug in a direction perpendicular to the magnetic field. The interaction between the current and the magnetic field generates a force on the slug normal to the plane formed by the current and field vectors. This force is aligned with the axis of the channel and causes the slug to reciprocate back and forth at the same frequency as the input current. The motion of the liquid gallium slug is used to compress the gas. Intake and discharge ducts are connected through check valves to both ends of the compressor channel. The purported advantages of the liquid gallium compressor are no contamination of the working fluid, high reliability, good efficiency, high pressure ratio capability, ease of vibration cancellation and small size and weight.
A new type of refrigerator compressor under development is a compressor that uses resonant sound waves. In a conventional refrigerator compressor, an oil-lubricated piston-and-cylinder device mechanically compresses refrigerant gas to produce cooling. In this new compressor, an acoustic drive, which functions somewhat like a bass loudspeaker, uses electrical power to set up resonant sound waves with pressure amplitudes up to 100 pounds per square inch. The sound waves then compress the refrigerant when they pass through a pair of high speed, 340-cycles-per-second, one way valves.
All of the above mentioned compressors have one serious drawback; they all contain moving parts, either pistons, valves, rotating vanes, etc. The present invention will go one step beyond the current compressor technology to eliminate moving parts in the traditional sense.